Multi-speed transmission

ABSTRACT

A transmission of the present invention has an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices may include clutches and brakes. The torque transmitting devices are selectively engageable in combinations of at least two to establish at least nine forward speed ratios and at least one reverse speed ratio.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices, and more particularly to a transmission havingnine or more speeds, four planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches or brakes, planetary gear arrangements and fixedinterconnections to achieve a plurality of gear ratios. The number andphysical arrangement of the planetary gear sets, generally, are dictatedby packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,four planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices are for example clutches and brakes.

In an aspect of the present invention a transmission is provided havingan input member, an output member, a first, second, third and fourthplanetary gear sets each having sun gears, carrier members and ringgears. The input member is continuously interconnected with the ringgear of the third planetary gear set. The output member is continuouslyinterconnected with the carrier member of the fourth planetary gear set.

Additionally, a first interconnecting member continuously interconnectsthe ring gear of the first planetary gear set with the carrier member ofthe second planetary gear set, a second interconnecting membercontinuously interconnects the carrier member of the first planetarygear set and the ring gear member of the second planetary gear set withthe stationary member, a third interconnecting member continuouslyinterconnects the sun gear member of the second planetary gear set withthe sun gear member of the third planetary gear set, a fourthinterconnecting member continuously interconnects the sun gear of thethird planetary gear set with the sun gear of the fourth planetary gearset. Further, a first torque transmitting device is selectivelyengageable to interconnect the carrier member of the second planetarygear set and the ring gear of the first planetary gear set with thecarrier member of the third planetary gear set, a second torquetransmitting device is selectively engageable to interconnect the ringgear member of the third planetary gear set and the input member withthe sun gear member of the first planetary gear set, a third torquetransmitting device is selectively engageable to interconnect the ringgear member of the third planetary gear set and the input member withthe ring gear of the fourth planetary gear set, a fourth torquetransmitting device is selectively engageable to interconnect thecarrier member of the third planetary gear set with the carrier of thefourth planetary gear set, a fifth torque transmitting device isselectively engageable to interconnect the sun gear of the fourthplanetary gear set with the stationary member and a sixth torquetransmitting device is selectively engageable to interconnect the ringgear of the fourth planetary gear set with the stationary member. Thetorque transmitting devices are selectively engageable in combinationsof at least two to establish at least nine forward speed ratios and atleast one reverse speed ratio between the input member and the outputmember.

It is thus an object of the present invention to provide a transmissionhaving four planetary gear sets.

It is a further object of the present invention to provide atransmission having nine forward speeds and at least one reverse.

It is a still further object of the present invention to provide atransmission having four planetary gear sets, a plurality of couplingmembers and a plurality of torque transmitting devices.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of a nine speed transmissionaccording to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of a nine speedtransmission according to the present invention; and

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that in the particular exampleprovided, the nine speed automatic transmission of the present inventionhas an arrangement of permanent mechanical connections between theelements of the four planetary gear sets. A first component or elementof a first planetary gear set is permanently coupled to a thirdcomponent or element of a second planetary gear set. A second componentor element of the first planetary gear set is permanently coupled to astationary member or ground. A first component or element of a secondplanetary gear set is permanently coupled to a first component orelement of a third planetary gear set and to a first component orelement of the fourth planetary gear set. Finally, a second component orelement of the second planetary gear set is permanently coupled to astationary member or ground.

Referring now to FIG. 1, an embodiment of a nine speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear set are each represented by a node. Therefore, a single levercontains three nodes: one for the sun gear, one for the planet gearcarrier, and one for the ring gear. The relative length between thenodes of each lever can be used to represent the ring-to-sun ratio ofeach respective gear set. These lever ratios, in turn, are used to varythe gear ratios of the transmission in order to achieve appropriateratios and ratio progression. Mechanical couplings or interconnectionsbetween the nodes of the various planetary gear sets are illustrated bythin, horizontal lines and torque transmitting devices such as clutchesand brakes are presented as interleaved fingers. If the device is abrake, one set of the fingers is grounded. Further explanation of theformat, purpose and use of lever diagrams can be found in SAE Paper810102, “The Lever Analogy: A New Tool in Transmission Analysis” byBenford and Leising which is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a fourth planetary gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C and an output shaft or member 22.

The input member 12 is coupled to the third node 18C of the thirdplanetary gear set 18. The output member 22 is coupled to the third node20C of the fourth planetary gear set 20. The first node 14A of the firstplanetary gear set 14 is coupled to the third node 16C of the secondplanetary gear set 16. The second node 14B of the first planetary gearset 14 is coupled to a stationary member or transmission housing 50. Thefirst node 16A of the second planetary gear set 16 is coupled to thefirst node 18A of the third planetary gear set 18 and to the first node20A of the fourth planetary gear set 20. The second node 16B of thesecond planetary gear set 16 is coupled to the stationary member ortransmission housing 50.

A first clutch 26 selectively connects the first node 14A of the firstplanetary gear set 14 with the second node 18B of the third planetarygear set 18. A second clutch 28 selectively connects the third node 14Cof the first planetary gear set 14 with the third node 18C of the thirdplanetary gear set 18. A third clutch 30 selectively connects the thirdnode 18C of the third planetary gear set 18 and input member 12 with thesecond node 20B of the fourth planetary gear set 20. A fourth clutch 32selectively connects the second node 18B of the third planetary gear set18 with the third node 20C of the fourth planetary gear set 20. A firstbrake 34 selectively connects the first node 20A of the fourth planetarygear set 20 with a stationary element or a transmission housing 50. Asecond brake 36 selectively connects the second node 20B of the fourthplanetary gear set 20 with a stationary element or the transmissionhousing 50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the nine speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches, brakes, and couplings arecorrespondingly presented whereas the nodes of the planetary gear setsnow appear as components of planetary gear sets such as sun gears, ringgears, planet gears and planet gear carriers.

For example, the planetary gear set 14 includes a sun gear member 14C, aring gear member 14A, and a planet gear carrier member 14B thatrotatably supports a set of planet gears 14D (only one of which isshown). The planet gears 14D are each configured to intermesh with boththe sun gear member 14C and the ring gear member 14A. The sun gearmember 14C is connected for common rotation with a first shaft orinterconnecting member 42. The ring gear member 14A is connected forcommon rotation with a second shaft or interconnecting member 44. Theplanet carrier member 14B is connected for common rotation with a thirdshaft or interconnecting member 46. The third shaft or interconnectingmember 46 is permanently connected to a stationary member ortransmission housing 50, thus restricts the rotation of third shaft orinterconnecting member 46 and planet carrier member 14B.

The planetary gear set 16 includes a sun gear member 16A, a ring gearmember 16B and a planet gear carrier member 16C that rotatably supportsa first set of planet gears 16D (only one of which is shown) and asecond set of planet gears 16E (only one of which is shown). The planetgears 16D are each configured to intermesh with both the sun gear member16A and the second set of planet gears 16E. The planet gears 16E areeach configured to intermesh with both the ring gear member 16B and thefirst set of planet gears 16D. The sun gear member 16A is connected forcommon rotation with a fourth shaft or interconnecting member 48. Thering gear member 16B is connected for common rotation with the thirdshaft or interconnecting member 46. The third shaft or interconnectingmember 46 is permanently connected to a stationary member ortransmission housing 50, thus restricts the rotation of third shaft orinterconnecting member 46 and ring gear member 16B. The planet carriermember 16C is connected for common rotation with the secondinterconnecting member 44.

The planetary gear set 18 includes a sun gear member 18A, a ring gearmember 18C and a planet gear carrier member 18B that rotatably supportsa set of planet gears 18D (only one of which is shown). The planet gears18D are each configured to intermesh with both the sun gear member 18Aand the ring gear member 18C. The sun gear member 18A is connected forcommon rotation with the fourth shaft or interconnecting member 48 andwith a fifth shaft or interconnecting member 52. The ring gear member18C is connected for common rotation with the input shaft or member 12.The planet carrier member 18B is connected for common rotation with asixth shaft or interconnecting member 54 and with a seventh shaft orinterconnecting member 56.

The planetary gear set 20 includes a sun gear member 20A, a ring gearmember 20B and a planet gear carrier member 20C that rotatably supportsa first set of planet gears 20D (only one of which is shown) and asecond set of planet gears 20E (only one of which is shown). The firstset of planet gears 20D are each configured to intermesh with both thesun gear member 20A and the second set of planet gears 20E. The secondset of planet gears 20E are configured to intermesh with both the ringgear member 20B and the first set of planet gears 20D. The sun gearmember 20A is connected for common rotation with the fifth shaft orinterconnecting member 52 and with an eighth shaft or interconnectingmember 58. The ring gear member 20B is connected for common rotationwith the ninth shaft or interconnecting member 60. The planet carriermember 20C is connected for common rotation with a tenth shaft orinterconnecting member 62 and with output shaft or member 22.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 22 is continuously connected with the final drive unitor transfer case (not shown).

The torque-transmitting mechanisms or the clutches 26, 28, 30, 32 andthe brakes 34 and 36 allow for selective interconnection of the shaftsor interconnecting members, members of the planetary gear sets and thehousing. For example, the first clutch 26 is selectively engageable toconnect the second shaft or interconnecting member 44 with the sixthshaft or interconnecting member 54. The second clutch 28 is selectivelyengageable to connect the input shaft or member 12 with the first shaftor interconnecting member 42. The third clutch 30 is selectivelyengageable to connect the input shaft or member 12 with the ninthinterconnecting shaft or member 60. The fourth clutch 32 is selectivelyengageable to connect the seventh shaft or interconnecting member 56with the tenth interconnecting shaft or member 62. The first brake 34 isselectively engageable to connect the eighth shaft or interconnectingmember 58 with a stationary element or the transmission housing 50 inorder to prevent the eighth shaft or interconnecting member 58 fromrotating relative to the transmission housing 50. The second brake 36 isselectively engageable to connect the ring gear member 20B with astationary element or the transmission housing 50 in order to preventthe ring gear member 20B from rotating relative to the transmissionhousing 50.

Referring now to FIGS. 2 and 3, the operation of the embodiment of thenine speed transmission 10 will be described. It will be appreciatedthat the transmission 10 is capable of transmitting torque from theinput shaft or member 12 to the output shaft or member 22 in at leastnine forward speed or torque ratios and at least one reverse speed ortorque ratio with a triple overdrive. Each forward and reverse speed ortorque ratio is attained by engagement of one or more of thetorque-transmitting mechanisms (i.e. first clutch 26, second clutch 28,third clutch 30, fourth clutch 32, first brake 34 and second brake 36),as will be explained below. FIG. 3 is a truth table presenting thevarious combinations of torque-transmitting elements that are activatedor engaged to achieve the various gear states. Actual numerical gearratios of the various gear states are also presented although it shouldbe appreciated that these numerical values are exemplary only and thatthey may be adjusted over significant ranges to accommodate variousapplications and operational criteria of the transmission 10. An exampleof the gear ratios that may be obtained using the embodiments of thepresent invention are also shown in FIG. 3. Of course, other gear ratiosare achievable depending on the gear diameter, gear teeth count and gearconfiguration selected.

To establish reverse gear, the second clutch 28 and the second brake 36are engaged or activated. The second clutch 28 connects the input shaftor member 12 with the first shaft or interconnecting member 42. Thesecond brake 36 connects the ring gear member 20B with a stationaryelement or the transmission housing 50 in order to prevent the ring gearmember 20B from rotating relative to the transmission housing 50.Likewise, the nine forward ratios are achieved through differentcombinations of clutch and brake engagement, as shown in FIG. 3.

It will be appreciated that the foregoing explanation of operation andgear states of the nine speed transmission 10 assumes, first of all,that all the clutches and brakes not specifically referenced in a givengear state are inactive or disengaged and, second of all, that duringgear shifts, i.e., changes of gear state, between at least adjacent gearstates, a clutch or brake engaged or activated in both gear states willremain engaged or activated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members; a first interconnecting member continuouslyinterconnecting the first member of the first planetary gear set withthe third member of the second planetary gear set; a secondinterconnecting member continuously interconnecting the second member ofthe first planetary gear set and the second member of the secondplanetary gear set with a stationary member; a third interconnectingmember continuously interconnecting the first member of the secondplanetary gear set with the first member of the third planetary gearset; a fourth interconnecting member continuously interconnecting thefirst member of the third planetary gear set with the first member ofthe fourth planetary gear set; and six torque transmitting devicesselectively engageable to interconnect one of the first, second, andthird members with at least one other of the first members, secondmembers, third members, and the stationary member, and wherein thetorque transmitting devices are selectively engageable in combinationsof at least two to establish at least nine forward speed ratios and atleast one reverse speed ratio between the input member and the outputmember.
 2. The transmission of claim 1 wherein a first of the six torquetransmitting devices is selectively engageable to interconnect at leastone of the first member of the first planetary gear set and the thirdmember of the second planetary gear set with the second member of thethird planetary gear set.
 3. The transmission of claim 2 wherein asecond of the six torque transmitting devices is selectively engageableto interconnect the third member of the first planetary gear set withthe input member and the third member of the third planetary gear set.4. The transmission of claim 3 wherein a third of the six torquetransmitting devices is selectively engageable to interconnect at leastone of the input member and the third member of the third planetary gearset with the second member of the fourth planetary gear set.
 5. Thetransmission of claim 4 wherein a fourth of the six torque transmittingdevices is selectively engageable to interconnect the second member ofthe third planetary gear set with the third member of the fourthplanetary gear set.
 6. The transmission of claim 5 wherein a fifth ofthe six torque transmitting devices is selectively engageable tointerconnect the first member of the fourth planetary gear set with thestationary member.
 7. The transmission of claim 6 wherein a sixth of thesix torque transmitting devices is selectively engageable tointerconnect the second member of the fourth planetary gear set with thestationary member.
 8. The transmission of claim 1 wherein the thirdmember of the first planetary gear set, the first member of the secondplanetary gear set, the first member of the third planetary gear set andthe first member of the fourth planetary gear set are sun gears, thesecond member of the first planetary gear set, the third member of thesecond planetary gear set, the second member of the third planetary gearset and the third member of the fourth planetary gear set are carriermembers and the first member of the first planetary gear set, the secondmember of the second planetary gear set, the third member of the thirdplanetary gear set and the second member of the fourth planetary gearset are ring gears.
 9. The transmission of claim 1 wherein the inputmember is continuously interconnected with the third member of the thirdplanetary gear set and wherein the output member is continuouslyinterconnected with the third member of the fourth planetary gear set.10. The transmission of claim 1 wherein two of the six torquetransmitting devices are brakes and four of the six torque transmittingdevices are clutches.
 11. The transmission of claim 1 wherein thestationary member is a transmission housing.
 12. A transmissioncomprising: an input member; an output member; first, second, third andfourth planetary gear sets each having first, second and third members,wherein the input member is continuously interconnected with the thirdmember of the third planetary gear set and wherein the output member iscontinuously interconnected with the third member of the fourthplanetary gear set; a first interconnecting member continuouslyinterconnecting the first member of the first planetary gear set withthe third member of the second planetary gear set; a secondinterconnecting member continuously interconnecting the second member ofthe first planetary gear set and the second member of the secondplanetary gear set with a stationary member; a third interconnectingmember continuously interconnecting the first member of the secondplanetary gear set with the first member of the third planetary gearset; a fourth interconnecting member continuously interconnecting thefirst member of the third planetary gear set with the first member ofthe fourth planetary gear set; a first torque transmitting deviceselectively engageable to interconnect at least one of the first memberof the first planetary gear set and the third member of the secondplanetary gear set with the second member of the third planetary gearset; a second torque transmitting device selectively engageable tointerconnect the third member of the first planetary gear set with theinput member and the third member of the third planetary gear set; athird torque transmitting device selectively engageable to interconnectat least one of the input member and the third member of the thirdplanetary gear set with the second member of the fourth planetary gearset; a fourth torque transmitting device selectively engageable tointerconnect the second member of the third planetary gear set with thethird member of the fourth planetary gear set; a fifth torquetransmitting device selectively engageable to interconnect the firstmember of the fourth planetary gear set with the stationary member; asixth torque transmitting device selectively engageable to interconnectthe second member of the fourth planetary gear set with the stationarymember; and wherein the torque transmitting devices are selectivelyengageable in combinations of at least two to establish at least nineforward speed ratios and at least one reverse speed ratio between theinput member and the output member.
 13. The transmission of claim 12wherein the third member of the first planetary gear set, the firstmember of the second planetary gear set, the first member of the thirdplanetary gear set and the first member of the fourth planetary gear setare sun gears, the second member of the first planetary gear set, thethird member of the second planetary gear set, the second member of thethird planetary gear set and the third member of the fourth planetarygear set are carrier members and the first member of the first planetarygear set, the second member of the second planetary gear set, the thirdmember of the third planetary gear set and the second member of thefourth planetary gear set are ring gears.
 14. The transmission of claim12 wherein the stationary member is a transmission housing.
 15. Atransmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having sun gears,carrier members and ring gears, wherein the input member is continuouslyinterconnected with the ring gear member of the third planetary gear setand wherein the output member is continuously interconnected with thecarrier member of the fourth planetary gear set; a first interconnectingmember continuously interconnecting the ring gear member of the firstplanetary gear set with the carrier member of the second planetary gearset; a second interconnecting member continuously interconnecting thecarrier member of the first planetary gear set and the ring gear memberof the second planetary gear set with a stationary member; a thirdinterconnecting member continuously interconnecting the sun gear memberof the second planetary gear set with the sun gear member of the thirdplanetary gear set; a fourth interconnecting member continuouslyinterconnecting the sun gear member of the third planetary gear set withthe sun gear member of the fourth planetary gear set; a first torquetransmitting device selectively engageable to interconnect at least oneof the ring gear member of the first planetary gear set and the carriermember of the second planetary gear set with the carrier member of thethird planetary gear set; a second torque transmitting deviceselectively engageable to interconnect the sun gear member of the firstplanetary gear set with the input member and the ring gear member of thethird planetary gear set; a third torque transmitting device selectivelyengageable to interconnect at least one of the input member and the ringgear member of the third planetary gear set with the ring gear member ofthe fourth planetary gear set; a fourth torque transmitting deviceselectively engageable to interconnect the carrier member of the thirdplanetary gear set with the carrier member of the fourth planetary gearset; a fifth torque transmitting device selectively engageable tointerconnect the sun gear member of the fourth planetary gear set withthe stationary member; a sixth torque transmitting device selectivelyengageable to interconnect the ring gear member of the fourth planetarygear set with the stationary member; and wherein the torque transmittingdevices are selectively engageable in combinations of at least two toestablish at least nine forward speed ratios and at least one reversespeed ratio between the input member and the output member.
 16. Thetransmission of claim 15 wherein the stationary member is a transmissionhousing.